<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    let arr1 = [1,3,5,7,9]
    let arr2 = [2,4,6,8,10]
    console.log(...arr1); // 展开一个数组
    let arr3 = [...arr1, ...arr2] //连接数组

    // 在函数中使用
    function sum(...numbers){
      return numbers.reduce((preValue, currentValue) => {
        return preValue + currentValue
      })
    }

    console.log(sum(1,2,3,4));

    let person = {name: 'tom',age:18}
    let person2 = person
    // console.log(...person);  // 报错，展开运算符不能展开对象
    let person3 = {...person}  // 包一个花括号就没问题了   而react里面是因为babel语法加react的加持，支持展开对象 {...person}  括号代表的是我要写表达式了
    let person4 = {...person,name:"张三"}
 </script>
</body>
</html>